TDN.100:20 :ܗ݂ܢܝܢ ܕܝܢ ܬܫܒܚ̈ܬܐ ܕܝܠܗ݀ ܢܬܐܡܪ̈ܢ ܗܟܢܐ ܒܢܝ݂ܚܘ݂ܬܐ‏ : thus all of those hymns of hers are to be said calmly
See the entire entry for nīḥū, nīḥūṯā n.f. calm